Question 304492
x(x+3)=80
x^2+3x-80=0
{{{x = (-b +- sqrt( b^2-4*a*c ))/(2*a) }}}
x=(-3+-sqrt[362-4*1*-80])/2*1
x=(-3+-sqrt9+320])/2
x=(-3+-sqrt329)/2
x=(-3+-18.138)/2
x=-3+18.138)/2
x=15.138/2
x=7.569 ans
7.569+3=10.569 ans.
Proof:
7.569*10.569=80
80~80